Rotary valves for managing fluid flows in medical systems

ABSTRACT

In one aspect, a valve includes a valve body rotatable about a central axis of the valve body, an interior channel adjacent the valve body for permitting a fluid to flow through an axial opening of the interior channel, and a plug within the interior channel that is movable between a first axial position at the axial opening and a second axial position spaced apart from the axial opening. In the first axial position, the plug closes the axial opening to prevent the fluid from flowing through the axial opening in a first direction and to prevent the fluid from flowing through the axial opening in a second direction that is opposite to the first direction. In the second axial position, the plug permits the fluid to flow through the axial opening into the interior channel in the first direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/776,588, filed on Dec. 7, 2018, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to rotary valves for managing fluid flows inmedical systems, such as fluid flows in dialysis systems.

BACKGROUND

Dialysis is a treatment used to support a patient with insufficientrenal function. The two principal dialysis methods are hemodialysis andperitoneal dialysis. During hemodialysis (“HD”), the patient's blood ispassed through a dialyzer of a dialysis machine while also passing adialysis solution or dialysate through the dialyzer. A semi-permeablemembrane in the dialyzer separates the blood from the dialysate withinthe dialyzer and allows diffusion and osmosis exchanges to take placebetween the dialysate and the blood stream. These exchanges across themembrane result in the removal of waste products, including solutes likeurea and creatinine, from the blood. These exchanges also regulate thelevels of other substances, such as sodium and water, in the blood. Inthis way, the dialysis machine acts as an artificial kidney forcleansing the blood.

During peritoneal dialysis (“PD”), the patient's peritoneal lateralchannel is periodically infused with dialysate. The membranous lining ofthe patient's peritoneum acts as a natural semi-permeable membrane thatallows diffusion and osmosis exchanges to take place between thesolution and the blood stream. These exchanges across the patient'speritoneum result in the removal of waste products, including soluteslike urea and creatinine, from the blood, and regulate the levels ofother substances, such as sodium and water, in the blood.

Automated PD machines called PD cyclers are designed to control theentire PD process so that it can be performed at home, usually overnightwithout clinical staff in attendance. This process is termed continuouscycler-assisted PD (CCPD). Many PD cyclers are designed to automaticallyinfuse, dwell, and drain dialysate to and from the patient's peritoneallateral channel. The treatment typically lasts for several hours, oftenbeginning with an initial drain cycle to empty the peritoneal lateralchannel of used or spent dialysate. The sequence then proceeds throughthe succession of fill, dwell, and drain phases that follow one afterthe other.

Various fluid paths within a dialysis system must be managed throughouta dialysis treatment via actuation of valves along the fluid paths.

SUMMARY

This disclosure relates to rotary valves for managing fluid flows inmedical systems, such as fluid flows in dialysis systems.

In one aspect, a valve includes a valve body rotatable about a centralaxis of the valve body, an interior channel adjacent the valve body forpermitting a fluid to flow through an axial opening of the interiorchannel, and a plug within the interior channel that is movable betweena first axial position at the axial opening and a second axial positionspaced apart from the axial opening. In the first axial position, theplug closes the axial opening to prevent the fluid from flowing throughthe axial opening in a first direction and to prevent the fluid fromflowing through the axial opening in a second direction that is oppositeto the first direction. In the second axial position, the plug permitsthe fluid to flow through the axial opening into the interior channel inthe first direction.

Embodiments may include one or more of the following features.

In some embodiments, the valve further includes a compressible memberwithin the interior channel that biases the plug to the first axialposition.

In certain embodiments, the valve body defines a cam positioned adjacentthe interior channel.

In some embodiments, the valve body is rotatable to a first rotationalposition in which a protrusion of the cam is aligned with and squeezesthe compressible member into a compressed configuration that exerts afirst cracking pressure on the plug, and a second rotational position inwhich the protrusion of the cam is aligned with and spaced apart fromthe compressible member to release the compressible member into anextended configuration that exerts a second cracking pressure on theplug, the second cracking pressure being less than the first crackingpressure.

In certain embodiments, the interior channel is a first interiorchannel, the compressible member is a first compressible member, and thevalve further includes a second interior channel and a secondcompressible member carried therein, the second interior channel and thesecond compressible member positioned adjacent the plug and opposite thefirst interior channel and the first compressible member.

In some embodiments, the valve body is rotatable to a first rotationalposition in which a protrusion of the cam is aligned with and squeezesthe first compressible member into a compressed configuration thatbiases the plug to the first axial position, and a second rotationalposition in which the protrusion of the cam is aligned with and spacedapart from the first compressible member to release the first and secondcompressible members into an extended configuration in which the secondcompressible member positions the plug at the second axial position toallow the fluid to flow through the axial opening in the first directionor to allow the fluid to flow through the axial opening and past theplug in the second direction.

In certain embodiments, the valve is configured such that the plug ismovable from the first axial position to the second axial position by apressure of the fluid flowing into the axial opening.

In some embodiments, the valve defines a lateral opening in the interiorchannel through which fluid can flow out of the interior channel.

In certain embodiments, the valve body defines a first exterior channelalong a first side of the valve body and a second exterior channel alonga second side of the valve body that is opposite the first side, thefirst and second exterior channels being in fluid communication with theinterior channel.

In some embodiments, the valve body is rotatable to a first rotationalposition in which the fluid flows in a third direction across the valvebody and past the first and second exterior channels and a secondrotational position in which the fluid flows in a fourth directionacross the valve body and along the first and second exterior channels,the fourth direction being opposite to the third direction.

In another aspect, a valve includes an interior channel for permitting afluid to flow through the valve and an opening to the interior channel,the opening including a circular portion and a tapered portion adjacentthe circular portion, the tapered portion having a maximum width that isless than a diameter of the circular portion, wherein the valve isrotatable about a central axis of the valve to adjust a position of across-sectional area of the opening with respect to a cross-sectionalarea of an inlet fluid line positioned to deliver the fluid to therotary valve.

Embodiments may include one or more of the following features.

In some embodiments, the circular portion of the interior channel is athrough channel that extends from a first side of the valve to a secondside of the valve that is opposite to the first side.

In certain embodiments, the tapered portion extends from the first sideof the valve and terminates at a location internal to the valve.

In some embodiments, the opening is a first opening disposed along thefirst side of the valve, the valve further including a second openingdisposed along the second side of the valve.

In certain embodiments, the valve is rotatable to a first rotatableposition in which the cross-sectional area of the inlet fluid line isaligned with the circular portion and is offset from of the taperedportion of the interior channel to permit a maximum fluid flow rate intothe interior channel.

In some embodiments, the valve is rotatable to a second rotatableposition in which the cross-sectional area of the inlet fluid line isoffset from the cross-sectional area of the interior channel to preventfluid flow into the interior channel.

In certain embodiments, a flow rate of the fluid increases from zero atthe second rotational position of the valve to the maximum flow rate asthe valve is rotated from the second rotational position to the firstrotational position.

In some embodiments, an axis of the opening is perpendicular to thecentral axis of the valve.

In certain embodiments, the opening is a first opening, the fluid is afirst fluid, and the inlet fluid line is a first inlet fluid line, thevalve further including a second opening to the interior channel that iscircumferentially offset from the first opening.

In some embodiments, the valve is rotatable to adjust a position of across-sectional area the second opening with respect to across-sectional area of the second inlet fluid line positioned todeliver a second fluid to the rotary valve to control a ratio at whichthe first and second fluids are mixed within the interior channel.

In another aspect, a medical system includes a medical fluid pumpingmachine including an actuator and a valve configured to be secured tothe medical fluid pumping machine such that the valve is operable withthe actuator. The valve includes a valve body rotatable about a centralaxis of the valve body, an interior channel adjacent the valve body forpermitting a fluid to flow through an axial opening of the interiorchannel, and a plug within the interior channel that is movable betweena first axial position at the axial opening and a second axial positionspaced apart from the axial opening. In the first axial position, theplug closes the axial opening to prevent the fluid from flowing throughthe axial opening in a first direction and to prevent the fluid fromflowing through the axial opening in a second direction that is oppositeto the first direction. In the second axial position, the plug permitsthe fluid to flow through the axial opening into the interior channel inthe first direction.

Embodiments may include one or more of the following features.

In some embodiments, the medical fluid pumping machine is a dialysismachine.

In certain embodiments, the medical fluid pumping machine furtherincludes a disposable medical fluid line set that includes the valve.

In some embodiments, the medical fluid pumping machine further includesa disposable medical fluid cassette that includes the valve.

In certain embodiments, the valve body defines an interface at which thevalve is engageable with the actuator and by which the valve isrotatable by the actuator.

In some embodiments, a shape of the interface is complementary to ashape of the actuator.

In another aspect, a medical system includes a medical fluid pumpingmachine including an actuator and a valve configured to be secured tothe medical fluid pumping machine such that the valve is operable withthe actuator. The valve includes an interior channel for permitting afluid to flow through the valve and an opening to the interior channel,the opening including a circular portion and a tapered portion adjacentthe circular portion, the tapered portion having a maximum width that isless than a diameter of the circular portion, wherein the valve isrotatable about a central axis of the valve to adjust a position of across-sectional area of the opening with respect to a cross-sectionalarea of an inlet fluid line positioned to deliver the fluid to therotary valve.

Embodiments may include one or more of the following features.

In some embodiments, the medical fluid pumping machine is a dialysismachine.

In certain embodiments, the medical system further includes a disposablemedical fluid line set that includes the valve.

In some embodiments, the medical system further includes a disposablemedical fluid cassette that includes the valve.

In certain embodiments, the valve body defines an interface at which thevalve is engageable with the actuator and by which the valve isrotatable by the actuator.

In some embodiments, a shape of the interface is complementary to ashape of the actuator.

Embodiments may provide one or more of the following advantages.

In some embodiments, owing to a capability of the rotary valve to beadjusted for selective fluid flow in reverse directions across therotary valve, a design of a medical system including the rotary valvecan be simplified to include a fewer total number of valves relative toconventional medical systems that require a dedicated valve for flowingfluid in each of the reverse directions. In certain embodiments, owingto a capability of the rotary valve to be adjusted for selectivelychanging a cracking pressure, a design of a medical system including therotary valve can be simplified to include a fewer total number of valvesrelative to conventional medical systems requiring dedicated valvesassociated with fixed cracking pressures. In some embodiments, owing toa capability of the rotary valve to be selectively enabled forpermitting fluid flow in one direction or disabled for permitting fluidflow in two, reverse directions, a design of a medical system includingthe rotary valve can be simplified to include a fewer total number ofvalves relative to conventional medical systems that require dedicatedcheck valves for limiting fluid flow to one direction and dedicatedbi-directional flow valves for permitting fluid flow in oppositedirections.

In certain embodiments, owing to a capability of the rotary valve to beadjusted for selectively controlling fluid flow rates and mixing ratios,a design of a medical system including the rotary valve can besimplified to include a fewer total number of valves relative toconventional medical systems that require a dedicated arrangement ofvalves and fluid flow lines for controlling fluid flow rates withingiven fluid flow lines. In some embodiments, a capability of the rotaryvalve to be adjusted for selective, automated control of fluid mixingcan eliminate the need for manual preparation of dialysate fluid andtherefore reduce a potential of errors in dialysate fluid compositionthat may otherwise occur with manual preparation. For example, utilizinga rotary valve in this manner to control fluid mixing may be useful formixing dry chemical pellets with respective amounts of water inpredetermined ratios for creating a dialysate fluid of a requiredcomposition.

In some embodiments, a reduced number of valves in association with anyof the above-discussed rotary valves may simplify other features of amedical system, such as a fluid flow line arrangement, a valve actuatorconfiguration, and valve control algorithms such that the medical systemcan operate in a robust manner. Other aspects, features, and advantageswill be apparent from the description, the drawings, and the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a rotary valve positioned to allow fluidflow through the rotary valve and in a first direction across the rotaryvalve.

FIG. 2 is a perspective view of the rotary valve of FIG. 1 positioned toallow fluid flow through the rotary valve and in a second, oppositedirection across the rotary valve.

FIG. 3 is a cross-sectional view of the rotary valve of FIG. 1positioned in the orientation shown in FIG. 1 and within a medicalsystem.

FIG. 4 is a cross-sectional view of the rotary valve of FIG. 1positioned in the orientation shown in FIG. 2 and within the medicalsystem of FIG. 3 .

FIG. 5 is a perspective, cross-sectional view of the rotary valve ofFIG. 1 positioned in the orientation shown in FIG. 1 .

FIG. 6 is a perspective, cross-sectional view of the rotary valve ofFIG. 1 positioned in the orientation shown in FIG. 2 .

FIG. 7 is a perspective side view of a first side of the rotary valve ofFIG. 1 .

FIG. 8 is a perspective side view of a second side of the rotary valveof FIG. 1 .

FIG. 9 is a perspective view of a rotary valve with an adjustablecracking pressure in a configuration that permits fluid flow through therotary valve.

FIG. 10 is a perspective view of the rotary valve of FIG. 9 in aconfiguration that prevents fluid flow through the rotary valve.

FIG. 11 is a perspective view of a valve body of the rotary valve ofFIG. 9 .

FIG. 12 is a perspective view of a rotary valve including a check valveconfiguration in an enabled state that prevents fluid flow through therotary valve.

FIG. 13 is a perspective view of the rotary valve of FIG. 12 with thecheck valve configuration in an enabled state that permits fluid flowthrough the rotary valve.

FIG. 14 is a perspective view of the rotary valve of FIG. 12 with thecheck valve configuration in a disabled state that permitsbi-directional fluid flow through the rotary valve.

FIG. 15 is a front perspective view of a rotary valve that allows anadjustable fluid flow rate through the rotary valve.

FIG. 16 is a rear perspective view of the rotary valve of FIG. 15 .

FIG. 17 is a perspective cross-sectional view of the rotary valve ofFIG. 15 .

FIG. 18 is a perspective view of the rotary valve of FIG. 15 installedwithin a medical system in a configuration that permits maximum fluidflow through the rotary valve.

FIG. 19 is a perspective view of the rotary valve of FIG. 15 installedwithin the medical system of FIG. 18 in a configuration that permitsreduced fluid flow through the rotary valve.

FIG. 20 is a graph that shows a cross-sectional area of a flow openingof a rotary valve as a function of a rotational position of the rotaryvalve, for both the rotary valve of FIG. 15 and a conventional rotaryvalve.

FIG. 21 is a perspective view of a medical system that includes two ofthe rotary valves of FIG. 15 oriented in selected rotational positionsfor achieving a desired fluid mixing ratio within the medical system.

FIG. 22 is a side perspective view of a rotary valve that allowsadjustable flow rates for multiple fluid flowing into the rotary valve.

FIG. 23 is a perspective view of the rotary valve of FIG. 22 installedwithin a medical system.

FIG. 24 is a perspective cross-sectional view of the rotary valve ofFIG. 22 within the medical system of FIG. 23 .

FIG. 25 is a schematic illustration of an example medical systemincluding multiple example rotary valves that can be operated to carryout a medical treatment.

DETAILED DESCRIPTION

FIGS. 1-8 illustrate various views of a rotary valve 100 that isdesigned to allow fluid flow through the rotary valve 100 in a singledirection 112 (e.g., a bulk flow direction) through the rotary valve orin a single, opposite direction 134 (e.g., a bulk flow direction) acrossthe rotary valve 100. The rotary valve 100 may be a component of amedical system 101 (e.g., a dialysis system) in which a medical fluid(e.g., dialysate) is flowed in a controlled manner through various fluidlines, such as fluid lines 103, 105. The rotary valve 100 includes avalve body 102, a spring 104 housed within the valve body 102, and aball bearing 106 housed within the valve body 102.

The valve body 102 is generally cylindrical in shape and defines aninterface 108 at which the rotary valve 100 can be engaged by a systemactuator (not shown) for rotating the rotary valve 100 about a centralaxis 110 of the valve body 102. The interface 108 is formed as areceptacle (e.g., a recessed surface) with a shape that is complimentaryto that of the system actuator and that indicates a fluid flowdirection. For example, the interface 108 has a “t” shape with a centralextension 114 that can be oriented parallel to the first fluid flowdirection 112 across the rotary valve 100 or oriented parallel to thesecond, opposite fluid flow direction 134 across the rotary valve 100.The valve body 102 also defines a flange 116 that seats against ahousing 107 of the medical system 101.

The valve body 102 further defines various features that direct fluidflow across the rotary valve 100. For example, the valve body 102defines an interior pocket 118 that contains the spring 104 and the ballbearing 106, a lateral opening 120 to the interior pocket 118, and anaxial opening 122 to the interior pocket 118. The valve body 102 furtherdefines an exterior channel 124 in fluid communication with andextending perpendicular to an axis of the lateral opening 120. The valvebody 102 also defines an interior channel 126 extending from the axialopening 122 in the interior pocket 118 to a central opening 128 alongthe central axis 110 of the valve body 102. The valve body 102 furtherdefines a lateral opening 130 extending perpendicularly from theinterior channel 126, and an exterior channel 132 in fluid communicationwith and extending perpendicularly to an axis of the lateral opening130.

Referring particularly to FIGS. 3-6 , the spring 104 is biased to anextended configuration that forces the ball bearing 106 to a position inwhich the ball bearing 106 abuts the axial opening 122 of the interiorpocket 118. A diameter of the ball bearing 106 is larger than a diameterof the axial opening 122 such that the ball bearing 106 closes (e.g.,fluidically seals) the axial opening 122 to any fluid flowing towardsthe axial opening 122 when the spring 104 is in the extendedconfiguration. In this manner, the ball bearing 106 acts as a plugwithin the interior pocket 118 that can prevent or permit fluid flowthrough the axial opening 122.

For fluid to flow through the rotary valve 100, fluid must flow into thelateral opening 130, into the interior channel 126, and towards theaxial opening 122 with a pressure great enough (e.g., a crackingpressure) to push the ball bearing 106 up from the axial opening 122(e.g., thereby compressing the spring 104) such that the fluid unseatsthe ball bearing 106 to allow fluid to flow from the interior channel126 up into the interior pocket 118. The diameter of the ball bearing106 is smaller than a diameter of the interior pocket 118 such thatfluid can flow up and around the ball bearing 106 within the interiorpocket 118 and out of the lateral opening 120. If fluid was to flow fromthe fluid line 105 and into the interior pocket 118 through the lateralopening 120, such fluid would urge the ball bearing 106 toward the axialopening 122, thereby seating the ball bearing 106 in the axial opening122 and preventing fluid from flowing out of the interior pocket 118through the axial opening 122. Accordingly, the spring 104, the ballbearing 106, and the interior pocket 118 together form a check valveconfiguration that allows fluid to flow only in a single bulk direction160 along the central axis 110 of the valve body 102, which istransverse to the flow directions 112, 134. For example, while moleculesof the fluid can flow in several different directions as the fluidtravels around the ball bearing 106, a bulk direction of the fluid flowis that of the bulk flow direction 160. The check valve configuration ofthe rotary valve 100 typically has a cracking pressure in a range ofabout 500 Pa to about 10,000 Pa.

Still referring to FIGS. 3-6 , the rotary valve 100 can be adjusted to afirst rotational position (shown in FIGS. 3 and 5 ) that allows fluid toflow only in the first direction 112 from the fluid line 103 to thefluid line 105 and to a second rotational position (shown in FIGS. 4 and6 ) that allows fluid to flow only in the second direction 134 from thefluid line 105 to the fluid line 103. In the first rotational positionof the rotary valve 100, the fluid line 103 is axially aligned with thelateral opening 130, and the housing 107 closes off the exterior channel132 along a circumference of the valve body 102. Similarly, the fluidline 105 is axially aligned with the lateral opening 120, and thehousing 107 closes off the exterior channel 124 along the circumferenceof the valve body 102. Accordingly, the lateral opening 130, theinterior channel 126, the axial opening 122, the interior pocket 118,and the lateral opening 120 together and sequentially form a first flowpath within the rotary valve 100 along which fluid can flow in the firstdirection 112 across the rotary valve 100 and in the bulk direction 160along the central axis 110.

In the second rotational position of the rotary valve 100, the fluidline 103 is aligned with a lower end of the exterior channel 124, andthe housing 107 defines a flow path along the exterior channel 124 andalong the circumference of the valve body 102. Similarly, the fluid line105 is aligned with an upper end of the exterior channel 132, and thehousing 107 defines a flow path along the exterior channel 132 and alongthe circumference of the valve body 102. Accordingly, the exteriorchannel 132, the lateral opening 128, the interior channel 126, theaxial opening 122, the interior pocket 118, the lateral opening 120, andthe exterior channel 124 together and sequentially form a second flowpath within the rotary valve 100 along which fluid can flow in thesecond direction 134 across the rotary valve, while still flowing in thebulk direction 160 along the central axis 110. Accordingly, fluid flowsin only the single bulk direction 160 along the central axis 110 of therotary valve 100 within both the first and second flow paths.

The interior pocket 118 of the valve body 102 typically has a diameterof about 6.4 mm to about 6.8 mm (e.g., about 6.6 mm). The axial opening122 in the interior pocket 118 typically has a diameter of about 3.9 mmto about 4.3 mm (e.g., about 4.1 mm). The ball bearing 106 typically hasa diameter of about 6.1 mm to about 6.5 mm (e.g., about 6.3 mm). Thelateral openings 120, 130 typically have a diameter of about 3.6 mm toabout 4.0 mm (e.g., about 3.8 mm). The exterior channels 124, 132typically have a length of about 15.3 mm to about 15.7 mm (e.g., about15.5 mm) and a thickness of about 0.7 mm to about 1.2 mm (e.g., about1.0 mm). The valve body 102 typically has an exterior diameter (e.g.,excluding the flange 116) of about 10.0 mm to about 10.4 mm (e.g., about10.2 mm) and a total height of about 26.5 mm to about 26.9 mm (e.g.,about 26.7 mm). The flange 116 is typically spaced from an upper end ofthe valve body 102 by a distance of about 4.9 mm to about 5.3 mm (e.g.,about 5.1 mm).

The valve body 102, the spring 104, and the ball bearing 106 are made ofmaterials that are corrosion resistant, bio-compatible, durable, andsuitable for manufacturing. For example, the valve body 102 is typicallymade of polyetherimide, the spring 104 is typically made of stainlesssteel, and the ball bearing 106 is typically made of stainless steel.Furthermore, the valve body 102 and the ball bearing 106 are typicallymanufactured respectively via injection molding and grinding/lapping.

Due to a capability of the rotary valve 100 to be adjusted for selectivefluid flow in reverse directions 112, 134 across the rotary valve 100, adesign of a medical system (e.g., a dialysis system) including therotary valve 100 can be simplified to include a fewer total number ofvalves relative to conventional medical systems that require a dedicatedvalve for flowing fluid in each of the reverse directions. The reducednumber of valves may simplify other features of the medical system, suchas a fluid flow line arrangement, a valve actuator configuration, andvalve control algorithms such that the medical system can operate in arobust manner.

In operation, the interface 108 on the valve body 102 can be engaged(e.g., urged) by an actuator of the medical system 101 to rotate (e.g.,spin) the rotary valve 100 about the central axis 110. For example,during a fill phase of a peritoneal dialysis treatment in which aperitoneal lateral channel of a patient is filled with fresh dialysate,the rotary valve 100 may be oriented in the first rotational position toensure that fluid flows only in the first direction 112 from the medicalsystem 101 toward the patient. Conversely, during a drain phase of theperitoneal dialysis treatment in which the peritoneal lateral channel ofthe patient is drained (e.g., emptied) of used (e.g., spent) dialysate,the rotary valve 100 may be oriented in the second rotational positionto ensure that fluid flows only in the second direction 134 from thepatient toward the medical system 101.

In some embodiments, a check valve configuration of a rotary valve mayhave an adjustable cracking pressure. For example, FIGS. 9-11 illustratevarious views of a rotary valve 200 with an adjustable cracking pressurethat is designed to allow fluid flow through the rotary valve 200 in asingle direction 212 across the rotary valve 200. The rotary valve 200may be a component of a medical system 201 (e.g., a dialysis system) inwhich a medical fluid (e.g., dialysate) is flowed in a controlled mannerthrough various fluid lines, such as fluid lines 203, 205. The rotaryvalve 200 includes a valve body 202, a shaft 218 adjacent the valve body202, a spring 204 housed within the shaft 218, and a ball bearing 206housed within the shaft 218.

A central portion 262 of the valve body 202 is generally cylindrical inshape and defines an interface 208 at which the rotary valve 200 can beengaged by a system actuator (not shown) for rotating the rotary valve200 about an axis 210 of the valve body 202. The interface 208 is formedas a receptacle (e.g., a recessed surface) with a shape that iscomplimentary to that of the system actuator. The valve body 202 alsodefines a flange 216 that seats against a housing 207 of the medicalsystem 201 and a cam 240 of variable radius. The cam 240 is sized tocompress the spring 204 to a maximum extent within the shaft 218 when aprotrusion 242 of the cam 240 is aligned with an axis 244 of the shaft218 and in contact with the spring 204. A central extension 214 of the“t” shaped interface 208 is oriented parallel to the protrusion 242 ofthe cam 240, such that the interface 208 provides a visual indicator ofa rotational position of the cam 240 (e.g. corresponding to a rotationalposition of the rotary valve 200, itself).

The spring 204 is biased to an extended configuration that forces theball bearing 206 to a position in which the ball bearing 206 abuts anaxial opening 222 of the shaft 218. A diameter of the ball bearing 206is larger than a diameter of the axial opening 222 such that the ballbearing 206 closes (e.g., fluidically seals) the axial opening 222 tofluid flow towards the axial opening 222 when the spring 204 is in theextended configuration.

For fluid to flow through the rotary valve 200, fluid must flow withinthe fluid line 203 towards the axial opening 122 with a pressure greatenough (e.g., a cracking pressure) to push the ball bearing 206 up fromthe axial opening 222 (e.g., thereby compressing the spring 204) suchthat the fluid unseats the ball bearing 206 to allow fluid to flow fromthe fluid line 203 into the shaft 218. As discussed above with respectto the rotary valve 100, the diameter of the ball bearing 206 is smallerthan an interior diameter of the shaft 218 such that fluid can flow upand around the ball bearing 206 within the shaft 218, out of a lateralopening 220 in the shaft 218, and into the fluid line 205. If fluid wasto flow from the fluid line 205 and into the shaft 218 through thelateral opening 220, such fluid would urge the ball bearing 206 towardthe axial opening 222 of the shaft 218, thereby seating the ball bearing206 in the axial opening 222 and preventing fluid from flowing out ofthe shaft 218 through the axial opening 222. Accordingly, the spring204, the ball bearing 206, and the shaft 218 together form a check valveconfiguration that allows fluid to flow only in a single direction 212across the rotary valve 200 and in a single bulk direction 260 along theaxis 244 of the shaft 218.

The cracking pressure required to unseat the ball bearing 206 from theaxial opening 222 can be adjusted by rotating the cam 240 (e.g., byrotating the valve body 202 that defines the cam 240). For example, thecracking pressure can be adjusted to a maximum value when the protrusion242 of the cam 240 is axially aligned with and in contact with thespring 204 such that the spring 204 is maximally compressed (as shown inFIG. 9 ). Conversely, the cracking pressure can be adjusted to a minimumvalue when the protrusion 242 of the cam 240 is axially aligned with andspaced apart from the spring 204 (e.g., facing a direction opposite thespring 204) such that the spring 204 is minimally compressed (as shownin FIG. 10 ). The check valve configuration of the rotary valve 200typically has a maximum cracking pressure in a range of about [500 Pa toabout 10,000 Pa and typically has a minimum cracking pressure in a rangeof about 500 Pa to about 1,000 Pa.

The shaft 218 typically has an interior diameter of about 6.4 mm toabout 6.8 mm (e.g., about 6.6 mm) and a length of about 12.5 mm to about12.9 mm (e.g., about 12.7 mm). The axial opening 222 in the shaft 218typically has a diameter of about [3.9] mm to about 4.3 mm (e.g., about4.1 mm). The ball bearing 206 typically has a diameter of about 6.1 mmto about 6.5 mm (e.g., about 6.3 mm). The lateral opening 220 typicallyhas a diameter of about 4.9 mm to about 5.3 mm (e.g., about 5.1 mm). Thecentral portion 262 of the valve body 202 typically has an exteriordiameter of about 10.0 mm to about 10.4 mm (e.g., about 10.2 mm) and atotal height of about 7.4 mm to about 7.8 mm (e.g., about 7.6 mm). Theflange 216 is typically spaced from an upper end of the valve body 202by a distance of about 4.9 mm to about 5.3 mm (e.g., about 5.1 mm). Thevalve body 202, the spring 204, and the ball bearing 206 arerespectively made of the same materials from which the valve body 102,the spring 104, and the ball bearing 106 are made and are manufacturedin the same manners.

The cam 240 is typically spaced from a lower, opposite end of the valvebody 202 by a distance of about 2.3 mm to about 2.7 mm (e.g., about 2.5mm). The cam 240 has a variable radius about the axis 210 of the valvebody 102. The protrusion 242 of the cam 240 typically has a length(e.g., from a cylindrical wall of the valve body 102) of about 2.3 mm toabout 2.7 mm (e.g., about 2.5 mm) and corresponds to the maximum radiusof the cam 240.

Due to a capability of the rotary valve 200 to be adjusted forselectively changing a cracking pressure, a design of a medical system(e.g., a dialysis system) including the rotary valve 200 can besimplified to include a fewer total number of valves relative toconventional medical systems requiring dedicated valves associated withfixed cracking pressures. As discussed above, the reduced number ofvalves may simplify other features of the medical system, such as afluid flow line arrangement, a valve actuator configuration, and valvecontrol algorithms such that the medical system can operate in a robustmanner.

In operation, the interface 208 on the valve body 202 can be engaged(e.g., urged) by an actuator of the medical system 201 to rotate (e.g.,spin) the valve body 202 about the axis 210 of the valve body 202 toadjust the cracking pressure of the rotary valve 200. Adjusting thecracking pressure of the rotary valve 200 may be beneficial in caseswhere valves with different cracking pressures are needed. For example,a check valve can be used to regulate the fluid pressure in a system, sothat the fluid pressure remains below the cracking pressure. In someembodiments of HD systems, the pressure of the dialysate fluid in thedialyzer is typically regulated.

In some embodiments, a check valve configuration can be enabled topermit flow in only a single bulk direction within a rotary valve anddisabled to additionally permit flow in a second, reverse bulk directionwithin the rotary valve. For example, FIGS. 12-14 illustrate twoconfigurations of a rotary valve 300 including such a configuration. Therotary valve 300 may be a component of a medical system 301 (e.g., adialysis system) in which a medical fluid (e.g., dialysate) is flowed ina controlled manner through various fluid lines, such as fluid lines303, 305.

The rotary valve 300 includes several components of the rotary valve 200that are arranged and function as described above with respect to therotary valve 200, such as the valve body 202, the shaft 218, the spring204, and the ball bearing 206. The flange 216 of the valve body 202seats against a housing 307 of the medical system 301. The rotary valve300 further includes a shaft 336 that is axially aligned with the shaft218 and a spring 338 contained within the shaft 336. The shaft 336typically has an interior diameter of about 3.9 mm to about 4.3 mm(e.g., about 4.1 mm) and a length of about 9.6 mm to about 10.0 mm(e.g., about 9.8 mm).

Referring particularly to FIGS. 12 and 13 , when the protrusion 242 ofthe cam 240 is axially aligned with and in contact with the spring 204such that the spring 204 is maximally compressed, the spring 204, theball bearing 206, and the shaft 218 together form a check valveconfiguration that allows fluid to flow in only the single bulkdirection 260 along the axis 244 of the shaft 218 when the pressure offluid flowing in the bulk direction 260 exceeds the cracking pressure ofthe check valve configuration, as discussed above with respect to therotary valve 200. As long as the cracking pressure of the check valveconfiguration exceeds that of fluid flowing through the shaft 336 in thedirection 260, the ball bearing 206 remains seated in the axial opening222 of the shaft 218 and compresses the spring 338 such that the spring338 is fully contained within the shaft 336, and such that fluid cannotflow through the shaft 218 in the bulk direction 260, as shown in FIG.12 .

However, once the pressure of the fluid flowing through the shaft 336 inthe direction 260 exceeds the cracking pressure of the check valveconfiguration, the fluid unseats the ball bearing 206 to flow throughthe shaft 218 and out of the lateral opening 220 in a direction 312across the rotary valve 300, and the spring 338 extends axially into theshaft 218, as shown in FIG. 13 . The check valve configuration of therotary valve 300 typically has a cracking pressure in a range of about500 Pa to about 10,000 Pa.

Referring particularly to FIG. 14 , when the protrusion 242 of the cam240 is axially aligned with and spaced apart from the spring 204 (e.g.,facing a direction opposite the spring 204) such that the spring 204 isminimally compressed, the force exerted by the spring 204 on the ballbearing 206, and therefore, the force exerted by the ball bearing 206 onthe spring 338, decreases to allow the spring 338 to extend into theshaft 218 and thereby unseat the ball bearing 206 from the axial opening222 of the shaft 218. With the ball bearing 206 unseated from the axialopening 222 and contained within the shaft 218, the spring 204, the ballbearing 206, and the shaft 218 no longer provide a check valveconfiguration that limits flow to only the bulk direction 260 along theshaft. Rather, fluid is permitted to flow around the ball bearing 206within the shaft 218 bi-directionally, either in the bulk direction 260along the axis 244 and in the direction 312 across the rotary valve 300,or in a reverse bulk direction 264 along the axis 244 and in a reversedirection 334 across the rotary valve 300 because the check valveconfiguration has been effectively disabled.

Due to a capability of the rotary valve 300 to be selectively adjustedfor permitting fluid flow in one direction or permitting fluid flow intwo, reverse directions, a design of a medical system (e.g., a dialysissystem) including the rotary valve 300 can be simplified to include afewer total number of valves relative to conventional medical systemsthat require dedicated check valves for limiting fluid flow to onedirection and dedicated bi-directional flow valves for permitting fluidflow in opposite directions. In operation, the interface 208 on thevalve body 202 can be engaged (e.g., urged) by an actuator of themedical system 301 to rotate (e.g., spin) the valve body 202 about theaxis 210 of the valve body 202 to enable or disable the check valveconfiguration of the rotary valve 300. Enabling or disabling the checkvalve configuration may be useful in cases where fluid flow in a reversedirection to that of a normal operational direction is beneficial. Forexample, HD systems are sometimes cleaned with disinfecting fluids. Insome examples, it may be beneficial for such disinfecting fluids to flowfreely in a direction that is reverse to that of a normal operationaldirection.

In some embodiments, a rotary valve can be designed for adjusting afluid flow rate through the rotary valve. For example, FIGS. 15-19illustrate such a rotary valve 400. The rotary valve 400 may be acomponent of a medical system 401 (e.g., a dialysis system) in which amedical fluid (e.g., dialysate) is flowed in a controlled manner throughvarious fluid lines, such as fluid lines 403, 405.

A valve body 402 of the rotary valve is generally cylindrical in shapeand defines an interface 408 at which the rotary valve 400 can beengaged by a system actuator (not shown) for rotating the rotary valve400 about an axis 410 of the valve body 402. The valve body 402 furtherdefines an interior channel 418 and a flange 416 that seats against ahousing 407 of the medical system 401. The interface 408 is formed as areceptacle (e.g., a recessed surface) with a shape that is complimentaryto that of the system actuator. Furthermore, a central extension 414 ofthe “t” shaped interface 408 is oriented parallel to a central axis 444of the interior channel 418.

The interior channel 418 provides a path by which fluid can flow fromthe fluid line 403, through the rotary valve 400, and into the fluidline 405. The interior channel 418 defines a central, cylindricalthrough channel 420 that defines the central axis 444. The interiorchannel 418 also defines two opposing lateral channels 422, 424 thatopen to and extend laterally from opposite sides of the through channel420. The lateral channels 422, 424 do not extend through a completewidth of the valve body 402 and therefore terminate at interior pointswithin the valve body 402. The lateral channels 422, 424 have agenerally triangular shape such that a width of the lateral channels422, 424 increases from relatively small closed tips 426, 428 torelatively large openings 430, 432 defined by the through channel 420.

Referring particularly to FIG. 18 , in a first rotational position ofthe rotary valve 400 in which the central axis 444 of the interiorchannel 418 is aligned with the fluid lines 403, 405, the rotary valve400 achieves a maximum extent to which a cross-sectional area of theinterior channel 420 (e.g., defined by a diameter of the through channel420) can open to the fluid lines 403, 405. Thus, the rate at which fluidflows through the rotary valve 400 is maximal when the rotary valve 400is oriented in the first rotational position.

Referring particularly to FIG. 19 , as the rotary valve 400 is rotatedclockwise such that an opening of the through channel 420 moves awayfrom an axis of the fluid lines 403, 405 and such that the peripheraledges of the lateral channels 422, 424 are moved to overlap the fluidlines 403, 405, the rotary valve 400 can achieve a minimum extent towhich the cross-sectional area of the interior channel 420 (e.g.,defined by a width of the triangular lateral channels 422, 424) opens tothe fluid lines 403, 405. Thus, the rate (e.g., the non-zero rate) atwhich fluid flows through the rotary valve 400 is minimal when the fluidlines 403, 405 just slightly overlap the tips 426, 428 of the lateralchannels 422, 424.

Referring particularly to FIG. 17 , in such a rotational position, fluidcan flow along a path 412 to sequentially flow from the fluid line 403into the lateral channel 422, into the through channel 420, into thelateral channel 424, and into the fluid line 405 to exit the rotaryvalve 400. Accordingly, inclusion of the angled, winged lateral channels422, 424 along the through channel 420 fine tunes a degree to whichfluid flow rates can be controlled through the rotary valve 400. Thiseffect is illustrated in FIG. 20 , which shows a cross-sectional area ofa flow opening of the interior channel 418 (e.g., including the throughchannel 420 and the lateral channels 422, 424) as a function ofrotational position of the rotary valve 400 and of a rotary valve withsimply a standard cylindrical through channel 420 (e.g., excludinglateral channels such as the lateral channels 422, 424).

The valve body 402 typically has an exterior diameter (e.g., excludingthe flange 416) of about 12.5 mm to about 12.9 mm (e.g., about 12.7 mm)and a total height of about 17.6 mm to about 18.0 mm (e.g., about 17.8mm). The flange 416 is typically spaced from an upper end of the valvebody 402 by a distance of about 4.9 mm to about 5.3 mm (e.g., about 5.1mm). The central through channel 420 typically has a diameter of about3.6 mm to about 4.0 mm (e.g., about 3.8 mm). Each of the lateralchannels 422, 424 typically has a length of about 4.1 mm to about 4.5 mm(e.g., about 4.3 mm) and a maximum width of about 1.6 mm to about 2.0 mm(e.g., about 1.8 mm). The valve body 402 is made of the same materialsfrom which the valve body 102 is made and is manufactured via the sametechniques.

FIG. 21 illustrates a medical system 501 including two of the rotaryvalves 400 (400 a, 400 b) for improving flow control when multiple inletfluid flows are combined to provide one outlet fluid flow. For example,the medical system 501 includes inlet fluid lines 503 a, 503 bdelivering fluid to the rotary valves 400 a, 400 b, subsequentintermediate fluid line 505 a, 505 b, a mix fluid line 507 that combinesfluid flows entering through the inlet fluid lines 503 a, 503 b, and anoutlet fluid line 509 from which a single, mixed fluid flows away fromthe rotary valves 400 a, 400 b.

A ratio at which the two entrant fluids are mixed can be controlled byselectively adjusting the rotational positions of the rotary valves 400a, 400 b. For example, a rotational position of the rotary valve 400 bprovides a larger flow area opening to the intermediate fluid line 505 bthan does a rotational position of the rotary valve 400 a to theintermediate fluid line 505 a. Thus, the rotational position of therotary valve 400 b allows a higher fluid flow rate therethrough thandoes the rotational position of the rotary valve 400 a.

Owing to a capability of the rotary valve 400 to be adjusted forselectively controlling fluid flow rates and mixing ratios, a design ofa medical system (e.g., a dialysis system) including the rotary valve400 can be simplified to include a fewer total number of valves relativeto conventional medical systems that require a dedicated arrangement ofvalves and fluid flow lines for controlling fluid flow rates withingiven fluid flow lines. As discussed above with respect to the rotaryvalves 100, 200, 300, the reduced number of valves may simplify otherfeatures of the medical system, such as a fluid flow line arrangement, avalve actuator configuration, and valve control algorithms such that themedical system can operate in a robust manner. Utilizing rotary valves400 in this manner may be useful in cases where two fluids need to beaccurately mixed (e.g., for an HD system that is operated to mix water,acid/acetate, and/or bicarbonate to prepare dialysate fluid).

FIGS. 22-24 illustrate a rotary valve 600 designed for adjustingmultiple fluid flow rates through the rotary valve 600. The rotary valve600 may be a component of a medical system 601 (e.g., a dialysis system)in which a medical fluid (e.g., dialysate) is flowed in a controlledmanner through various fluid lines, such as fluid lines 603, 605, 607.

A valve body 602 of the rotary valve is generally cylindrical in shapeand defines an interface 608 and a flange 616 that are substantiallysimilar in construction and function to the interface 408 and the flange416 of the rotary valve 400. The valve body 602 further defines aninterior channel 618 that is centered on a central axis 610 of therotary valve 600 and that provides a fluid path by which fluid can flowfrom the inlet fluid lines 603, 605, through the rotary valve 600, andinto the outlet fluid line 609. The valve body 602 also defines an axialopening 620 at a lower end of the interior channel 618 and two lateralopenings 622, 624. The lateral openings 622, 624 respectively includecylindrical portions 630, 632 that open to triangular portions 646, 648.A width of the triangular portions 646, 648 respectively increases fromrelatively small closed tips 626, 628 to a maximum width along thecylindrical portions 630, 632.

Using the lateral opening 622 as an example, in a first rotationalposition of the rotary valve 600 in which a central axis 644 of thelateral opening 622 is aligned with that of the fluid line 603, therotary valve 600 achieves a maximum extent to which a cross-sectionalarea of the lateral opening 622 (e.g., defined by a diameter of thecylindrical portion 630) can open to the fluid line 603. Thus, the rateat which fluid flows through the lateral opening 622 is maximal in thefirst rotational position. As the rotary valve 600 is rotated clockwisesuch that the cylindrical portion 630 moves away from the fluid line 603and such that the triangular portion 646 is moved to overlap the fluidline 603, the rotary valve 600 can achieve a minimum extent to which thecross-sectional area of the lateral opening 622 (e.g., defined by awidth of the triangular portion 646) opens to the fluid line 603. Thus,the rate (e.g., the non-zero rate) at which fluid flows through thelateral opening 622 is minimal when the fluid line 603 just slightlyoverlaps the tip 626 of the lateral opening 622. Accordingly, inclusionof the triangular portion 646 along the cylindrical portion 630 finetunes a degree to which the fluid flow rate can be controlled throughthe lateral opening 622, as discussed above with respect to the interiorchannel 418 of the rotary valve 400. In a similar manner, the fluid flowrate can be controlled from the fluid line 605 through the lateralopening 624.

While the fluid lines 603, 605 are located at a same angular positionabout a circumference of the valve body 602 (as shown in FIG. 23 ), thelateral openings 622, 624 are located at different angular positionsabout the circumference of the valve body 602 (e.g., the lateralopenings 622, 624 are circumferentially offset from each other, as shownin FIG. 24 ). Therefore, a ratio at which two entrant fluids are mixedwithin the interior channel 618 can be controlled by adjusting therotational position of the rotary valve 600. In the example rotary valve600, the lateral opening 622 is positioned clockwise of the lateralopening 624 such that at any given rotational position, fluid flows at alower rate through the lateral opening 622 than through the lateralopening 624. The axial opening 620 of the rotary valve 600 delivers amixed fluid to a lateral channel 611 of the housing 607 that is beneaththe rotary valve 600 and that is fixed with respect to a position of theoutlet fluid line 609.

Utilizing a rotary valve 600 in this manner to control fluid mixing maybe useful for mixing dry chemical pellets with respective amounts ofwater in predetermined ratios for creating a dialysate fluid of arequired composition. This capability of the rotary valve 600 to beadjusted for selective, automated control of fluid mixing can eliminatethe need for manual preparation of dialysate fluid and therefore reducea potential of errors in dialysate fluid composition that may otherwiseoccur with manual preparation.

The valve body 602 typically has an exterior diameter (e.g., excludingthe flange 616) of about 10.0 mm to about 10.4 mm (e.g., about 10.2 mm)and a total height of about 23.9 mm to about 24.3 mm (e.g., about 24.1mm). The flange 616 is typically spaced from an upper end of the valvebody 602 by a distance of about 4.9 mm to about 5.3 mm (e.g., about 5.1mm). The interior channel 618 (e.g., and therefore the axial opening620) typically has a diameter of about 6.1 mm to about 6.5 mm (e.g.,about 6.3 mm). The cylindrical portions 630, 632 of the lateral openings622, 624 typically have a diameter of about 3.6 mm to about 4.0 mm(e.g., about 3.8 mm). The triangular portions 646, 648 of the lateralopenings 622, 624 typically have a length of about 4.1 mm to about 4.5mm (e.g., about 4.3 mm) and a maximum width of about 1.6 mm to about 2.0mm (e.g., about 1.8 mm). The valve body 602 is made of the samematerials from which the valve body 102 is made and is manufactured viathe same techniques.

FIG. 25 illustrates an example dialysis system 701 that includes rotaryvalves 700. In some embodiments, the dialysis system 701 can representseveral different types of systems, including but not limited to an HDsystem, a PD system, a hemofiltration system, a hemodiafiltrationsystem, an apheresis system, a dialysate generation system, or a waterpurification system. In some embodiments, the rotary valves 700 mayrepresent any of the above-discussed rotary valves 100, 200, 300, 400,600. The dialysis system 701 includes an example disposable fluidcassette 715 to which the rotary valves 700 and multiple fluid lines 703are secured. The cassette 715, the rotary valves 700, and the fluidlines 703 together form a disposable fluid line cassette. The exampledialysis system 701 can be operated to carry out any of the variousmedical treatments described above with respect to the rotary valves100, 200, 300, 400, 600.

While the above-discussed rotary valves 100, 200, 300, 400, 600 havebeen described and illustrated as including certain dimensions, sizes,shapes, and materials, in some embodiments, rotary valves that aresubstantially similar in structure and function to the above-discussedrotary valves 100, 200, 300, 400, 600 may include one or more differentdimensions, sizes, shapes, and materials. Furthermore, while the rotaryvalves 100, 200, 300, 400, 600 have been described and illustrated asbeing positioned in certain arrangements and configurations in themedical systems 101, 201, 301, 401, 501, 601 and used in certainprocesses for managing medical fluids, in some embodiments, the rotaryvalves 100, 200, 300, 400, 600 maybe positioned in other arrangementsand configurations within a medical system (e.g., such as an HD system,a PD system, a hemofiltration system, a hemodiafiltration system, anapheresis system, a dialysate generation system, or a water purificationsystem), used in other processes for managing medical fluids, or used inother, non-medical systems for managing other types of fluids.

While the above-discussed actuator interfaces 108, 208, 308, 408, 608have been described and illustrated as having a “t” shape, in someembodiments, a rotary valve that is substantially similar inconstruction and function to any of the rotary valves 100, 200, 300,400, 600 may include an actuator interface of a different shape (e.g.,either a symmetric or non-symmetric shape) for engagement with acorresponding system actuator.

Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A valve, comprising: a valve body that isrotatable about a central axis of the valve body and that defines: anelongate exterior channel extending axially along an outer surface ofthe valve body, and an interior channel in fluid communication with theelongate exterior channel and extending axially within the valve bodyfor permitting a fluid to flow through an axial opening of the interiorchannel; and a plug within the interior channel that is movable between:a first axial position at the axial opening in which the plug closes theaxial opening to prevent the fluid from flowing through the axialopening in a first direction and to prevent the fluid from flowingthrough the axial opening in a second direction that is opposite to thefirst direction, and a second axial position spaced apart from the axialopening in which the plug permits the fluid to flow through the axialopening into the interior channel in the first direction.
 2. The valveof claim 1, further comprising a compressible member within the interiorchannel that biases the plug to the first axial position.
 3. The valveof claim 2, wherein the valve is configured such that the plug ismovable from the first axial position to the second axial position by apressure of the fluid flowing into the axial opening.
 4. The valve ofclaim 1, wherein the valve defines a lateral opening in the interiorchannel through which fluid can flow out of the interior channel.
 5. Thevalve of claim 4, wherein the lateral opening is in fluid communicationwith the elongate exterior channel.
 6. The valve of claim 1, wherein theelongate exterior channel is a first elongate exterior channel extendingalong a first side of the valve body, and wherein the valve body furtherdefines a second elongate exterior channel extending axially along theouter surface of a second side of the valve body that is opposite thefirst side, the second elongate exterior channel being fluidlycommunicatable with the interior channel.
 7. The valve of claim 6,wherein the valve body is rotatable to: a first rotational position inwhich the fluid flows in a third direction across the valve body andpast the first and second elongate exterior channels, and a secondrotational position in which the fluid flows in a fourth directionacross the valve body and along the first and second elongate exteriorchannels, the fourth direction being opposite to the third direction. 8.The valve of claim 1, wherein the elongate exterior channel forms atleast a portion of a fluid flow path along the outer surface of thevalve body.
 9. A medical system, comprising: a medical fluid pumpingmachine comprising an actuator; and a valve configured to be secured tothe medical fluid pumping machine such that the valve is operable withthe actuator, the valve comprising: a valve body that is rotatable abouta central axis of the valve body and that defines: an elongate exteriorchannel extending axially along an outer surface of the valve body, andan interior channel in fluid communication with the elongate exteriorchannel and extending axially within the valve body for permitting afluid to flow through an axial opening of the interior channel, and aplug within the interior channel that is movable between: a first axialposition at the axial opening in which the plug closes the axial openingto prevent the fluid from flowing through the axial opening in a firstdirection and to prevent the fluid from flowing through the axialopening in a second direction that is opposite to the first direction,and a second axial position spaced apart from the axial opening in whichthe plug permits the fluid to flow through the axial opening into theinterior channel in the first direction.
 10. The medical system of claim9, wherein the medical fluid pumping machine is a dialysis machine. 11.The medical system of claim 9, further comprising a disposable medicalfluid line set that comprises the valve.
 12. The medical system of claim9, further comprising a disposable medical fluid cassette that comprisesthe valve.
 13. The medical system of claim 9, wherein the valve bodydefines an interface at which the valve is engageable with the actuatorand by which the valve is rotatable by the actuator.
 14. The medicalsystem of claim 13, wherein a shape of the interface is complementary toa shape of the actuator.
 15. A valve, comprising: a valve body that isrotatable about a central axis of the valve body and that defines a cam;a first interior channel positioned adjacent the cam of the valve body,the first interior channel permitting a fluid to flow through an axialopening of the interior channel; a plug within the first interiorchannel that is movable between: a first axial position at the axialopening in which the plug closes the axial opening to prevent the fluidfrom flowing through the axial opening in a first direction and toprevent the fluid from flowing through the axial opening in a seconddirection that is opposite to the first direction, and a second axialposition spaced apart from the axial opening in which the plug permitsthe fluid to flow through the axial opening into the first interiorchannel in the first direction; a first compressible member within thefirst interior channel that biases the plug to the first axial position;a second interior channel; and a second compressible member within thesecond interior channel, wherein the second interior channel and thesecond compressible member are positioned adjacent the plug and oppositethe first interior channel and the first compressible member.
 16. Thevalve of claim 15, wherein the valve body is rotatable to: a firstrotational position in which a protrusion of the cam is aligned with andsqueezes the first compressible member into a compressed configurationthat exerts a first cracking pressure on the plug, and a secondrotational position in which the protrusion of the cam is aligned withand spaced apart from the first compressible member to release the firstcompressible member into an extended configuration that exerts a secondcracking pressure on the plug, the second cracking pressure being lessthan the first cracking pressure.
 17. The valve of claim 15, wherein thevalve body is rotatable to: a first rotational position in which aprotrusion of the cam is aligned with and squeezes the firstcompressible member into a compressed configuration that biases the plugto the first axial position, and a second rotational position in whichthe protrusion of the cam is aligned with and spaced apart from thefirst compressible member to release the first and second compressiblemembers into an extended configuration in which the second compressiblemember positions the plug at the second axial position to allow thefluid to flow through the axial opening in the first direction or toallow the fluid to flow through the axial opening and past the plug inthe second direction.